In recent years, an organic EL display device is attracting attention as a flat screen display device. Unlike liquid crystal display devices, organic EL display devices are self-light emitting and therefore do not require a backlight and the like and have excellent characteristics such as being able to obtain high contrast.
However, a light emitting layer of an organic EL display device easily degrades when infiltrated by water which leads to the occurrence of non-lit regions called dark spots. In order to solve such problems, a sealing film is arranged in many organic EL display devices in order to prevent the infiltration of water. An organic EL display device described in Japanese Laid Open Patent Publication 2010-027561 is known for example as an organic EL display device arranged with a sealing film.
As is described in Japanese Laid Open Patent Publication 2010-027561, it is preferred to use an inorganic film which is transparent and has a high water prevention function as a sealing film. However, when defects in an inorganic film are present, there is a danger of an infiltration path for water being produced via the defects. Since it is difficult to form an inorganic film with completely no defects, it is effective to increase water resistance by stacking a plurality of inorganic films.
Other than incidental objects, those due to foreign objects or due to unevenness could be present as defects in an inorganic film. Even when a plurality of inorganic films is stacked above defects caused by foreign objects or unevenness, since there is a tendency for such defects to be passed up to an upper layer, it is desirable to perform leveling by interposing an organic film between two inorganic films.
However, since an organic film easily allows water to pass through, when defects are present in each of a plurality of stacked inorganic films, an infiltration path for water is formed via the organic film. Although it is thought that water which infiltrates via such an infiltration path requires considerable time to reach an organic EL light emitting layer, it is desirable not to delay the arrival time of water but to use a sealing film having a structure whereby it is difficult for the infiltration path of water itself to be formed in order to increase reliability of the product.
Such a problem affects not only organic EL display devices but all display devices than may degrade due to the infiltration of water.
Therefore, one aim of the present invention is to provide a display device arranged with a sealing film in which it is difficult for an infiltration path of water to be formed.